Cloud computing offers a new way of Information Technology (IT) services by re-arranging various resources (e.g., storage, computing and services) and providing them to users based on user's demands. Cloud computing provides a big resource pool by linking network resources together. It has desirable properties, such as scalability, elasticity, fault-tolerance, and pay-per-use. Thus, it becomes a promising service platform, rearranging the structure of IT.
One of the most important and typical cloud services is data storage. In the cloud computing, various cloud service providers (CSPs) provide huge volumes of storage to help users to save their data, such as, photos, contacts, emails, etc. But duplicated data may be stored at the cloud by a same user or different users, especially for shared data. Although the cloud storage space is huge, this kind of duplication could greatly waste networking resources, consume a lot of power energy, increase operation cost, or make data management complicated.
Thus, it would be an advancement to provide methods and systems that allow for store duplicated data at cloud with proper access control so as to ensure data security and privacy and at the same time save storage spaces.